U.S. patent application number 15/714997 was filed with the patent office on 2018-02-22 for biosensor.
The applicant listed for this patent is KYOCERA CORPORATION. Invention is credited to Toru Fukano, Atsuomi Fukuura, Yuji Kishida, Hideharu Kurioka, Hiroyasu Tanaka.
Application Number | 20180052139 15/714997 |
Document ID | / |
Family ID | 47601271 |
Filed Date | 2018-02-22 |
United States Patent
Application |
20180052139 |
Kind Code |
A1 |
Fukuura; Atsuomi ; et
al. |
February 22, 2018 |
BIOSENSOR
Abstract
A biosensor, including: a first cover member comprising an
element-accommodating recess in an upper face thereof; a detection
element using a surface acoustic wave, the detection element
including an element substrate accommodated in the
element-accommodating recess, and at least one detection unit
located on an upper face of the element substrate configured to
perform detection of an analyte; and a second cover member joined
to the first cover member and covering the detection element, and
including an inflow port from which the analyte flows in and a
groove which extends from the inflow port to at least above the at
least one detection unit and constitutes a capillary.
Inventors: |
Fukuura; Atsuomi;
(Seika-cho, JP) ; Fukano; Toru; (Seika-cho,
JP) ; Kishida; Yuji; (Seika-cho, JP) ; Tanaka;
Hiroyasu; (Seika-cho, JP) ; Kurioka; Hideharu;
(Kizugawa-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KYOCERA CORPORATION |
Kyoto |
|
JP |
|
|
Family ID: |
47601271 |
Appl. No.: |
15/714997 |
Filed: |
September 25, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14123752 |
Mar 4, 2014 |
9772310 |
|
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PCT/JP2012/069348 |
Jul 30, 2012 |
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15714997 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 29/02 20130101;
G01N 2291/0256 20130101; G01N 2291/0423 20130101; G01N 33/48707
20130101; G01N 29/022 20130101; G01N 2291/0255 20130101; G01N
29/222 20130101 |
International
Class: |
G01N 29/02 20060101
G01N029/02; G01N 29/22 20060101 G01N029/22; G01N 33/487 20060101
G01N033/487 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 28, 2011 |
JP |
2011-165163 |
Mar 23, 2012 |
JP |
2012-067617 |
Claims
1. A biosensor, comprising: a first cover member comprising an
element-accommodating recess in an upper face thereof; a detection
element using a surface acoustic wave, the detection element
comprising an element substrate accommodated in the
element-accommodating recess, and at least one detection unit
located on an upper face of the element substrate configured to
perform detection of an analyte; and a second cover member joined
to the first cover member and covering the detection element, and
comprising an inflow port from which the analyte flows in and a
groove which extends from the inflow port to at least above the at
least one detection unit and constitutes a capillary.
2. The biosensor according to claim 1, wherein a gap exists between
a side face of the detection element and inner walls of the
element-accommodating recess.
3. The biosensor according to claim 2, wherein a height of the
upper face of the element substrate from a bottom face of the
element-accommodating recess is equal to or lower than a depth of
the element-accommodating recess.
4. The biosensor according to claim 1, wherein the groove extends
from the inflow port toward the at least one detection unit past
the at least one detection unit, and the second cover member
further comprises a vent hole connected to the groove.
5. The biosensor according to claim 1, wherein the first cover
member comprises a first board with a flat shape, and a second
board joined to an upper face of the first board and comprising a
recess-forming through hole, and a bottom face of the
element-accommodating recess is the upper face of the first board,
and inner walls of the element-accommodating recess are inner walls
of the recess-forming through hole.
6. The biosensor according to claim 1, wherein the second cover
member comprises a third board with a flat shape comprising a notch
which penetrates in a thickness direction of the third board, and a
fourth plate with a flat shape joined to an upper face of the third
board, and a bottom face of the groove is a lower face of the
fourth board located above the notch, and inner walls of the groove
are inner walls of the notch.
7. The biosensor according to claim 1, wherein the detection
element further comprises: a first IDT electrode located on the
upper face of the element substrate configured to generate elastic
waves to be propagated toward the at least one detection unit, a
second IDT electrode located on the upper face of the element
substrate configured to receive the elastic waves passing through
the at least one detection unit, a first protective member which
comprises a first recess, is located on the upper face of the
element substrate, and seals the first IDT electrode within a first
vibration space surrounded by inner faces of the first recess and
the upper face of the element substrate, and a second protective
member which comprises a second recess, is located on the upper
face of the element substrate, and seals the second IDT electrode
within a second vibration space surrounded by inner faces of the
second recess and the upper face of the element substrate.
8. The biosensor according to claim 7, wherein the detection
element further comprises a first extracting electrode led out from
the first IDT electrode in an opposite direction of a side of the
at least one detection unit, and comprises an end located on an
outer side of the first protective member, and a second extracting
electrode led out from the second IDT electrode in an opposite
direction of a side of the at least one detection unit, and
comprises an end located on an outer side of the second protective
member.
9. The biosensor according to claim 6, wherein the detection
element further comprises: a first IDT electrode located on the
upper face of the element substrate configured to generate elastic
waves to be propagated toward the at least one detection unit, a
second IDT electrode located on the upper face of the element
substrate configured to receive the elastic waves passing through
the at least one detection unit, a first protective member which
comprises a first recess, is located on the upper face of the
element substrate, and seals the first IDT electrode within a first
vibration space surrounded by inner faces of the first recess and
the upper face of the element substrate, and a second protective
member which comprises a second recess, is located on the upper
face of the element substrate, and seals the second IDT electrode
within the second vibration space surrounded by inner faces of the
second recess and the upper face of the element substrate, the
detection element further comprises: a first extracting electrode
led out from the first IDT electrode in an opposite direction of a
side of the at least one detection unit, and comprises an end
located on an outer side of the first protective member, and a
second extracting electrode led out from the second IDT electrode
in an opposite direction of a side of the at least one detection
unit, and comprises an end located on an outer side of the second
protective member, the third board further comprises a first
through hole and a second through hole on both sides of the notch,
in a direction orthogonal to the direction in which the notch
extends, the first through hole being located on the first
extracting electrode and the second through hole being located on
the second extracting electrode, and a first partition, which is a
portion between the notch and the first through hole of the third
board, is located above the first protective member, and a second
partition, which is a portion between the notch and the second
through hole of the third board, is located above the second
protective member.
10. The biosensor according to claim 9, wherein the first partition
is located above the first protective member with a gap
therebetween, and the second partition is located above the second
protective member with a gap therebetween.
11. The biosensor according to claim 10, further comprising: a
first insulating member covering a portion of the first extracting
electrode located outside of the first protective member; and a
second insulating member covering a portion of the second
extracting electrode located outside of the second protective
member.
12. The biosensor according to claim 1, wherein the detection
element comprises a plurality of detection units, and the plurality
of detection units is arranged along a direction in which the
groove extends.
13. A biosensor, comprising: a mounting member comprising an inflow
port into which an analyte flows in, at an end thereof, and a
groove connected to the inflow port on an upper face thereof; a
detection element using a surface acoustic wave, the detection
element comprising an element substrate, a detection unit and at
least one electrode located on a surface of the element substrate,
the detection unit being configured to perform detection of the
analyte the detection element being mounted on the mounting member
with the detection unit and being located above the groove; and a
cover member which comprises an element-accommodating recess, and
is joined to the mounting member with the detection element
accommodated in the element-accommodating recess.
14. A biosensor, comprising: a cover member comprising an inflow
port for an analyte, a groove-shaped channel connected to the
inflow port and constituting a capillary, and a recessed space
connected to the channel; and a detection element using a surface
acoustic wave, the detection element comprising an element
substrate accommodated in the space, and a detection unit which is
located on an upper face of the element substrate and reacts with a
component included in the analyte.
15. The biosensor according to claim 14, wherein inner faces of the
channel are hydrophilic.
16. The biosensor according to claim 1, further comprising an
assisting board introduced between the first cover member and the
second cover member, wherein the detection element further
comprises a frame member located on the upper face of the element
substrate and surrounding the at least one detection unit, and
wherein the assisting board blocks off a portion of the frame
member surrounding the at least one detection unit and a gap
between side faces of the at least one detection unit and inner
walls of the element-accommodating recess, and comprises a first
hole portion connecting from the groove to inside a frame of the
frame member surrounding the at least one detection unit.
17. The biosensor according to claim 16, wherein the assisting
board further comprises a second hole portion connecting from the
groove to inside the frame of the frame member surrounding the at
least one detection unit, and the first hole portion is located
closer to the inflow port than the second hole portion.
18. The biosensor according to claim 1, further comprising an
assisting board between the first cover member and the second cover
member, wherein the assisting board comprises a hole portion at a
region overlapping with the element substrate, and wherein inner
walls of the hole portion are located further inside than a
perimeter of the upper face of the element substrate in plan view.
Description
TECHNICAL FIELD
[0001] The present invention relates to a biosensor capable of
performing measurement regarding properties of liquid analyte
specimens or measurement regarding components included in the
liquid.
BACKGROUND ART
[0002] There are known biosensors which use detection elements such
as surface acoustic wave devices to perform measurement regarding
properties of liquid analytes or measurement regarding components
of the liquid (for example, see PTLs 1 through 3).
[0003] For example, a biosensor using a surface acoustic wave
device is configured with a detection unit, which reacts with
components included in analyte specimens, on a piezoelectric
substrate. The properties or components of the liquid analyte are
detected by measuring change in surface acoustic waves propagating
through this detection unit. Measurement methods using surface
acoustic wave devices and the like are advantageous over other
measurement methods (the enzyme method, for example), in that
multiple detection formats can be handled.
[0004] However, none of the conventional biosensors using detection
elements such as surface acoustic wave devices have mechanisms to
suction liquid themselves. This has necessitated, in order to feed
the analyte to the detection unit, a task of first suctioning the
specimen using equipment such as a micropipette and then feeding
the suctioned specimen to the detection unit, which makes the
procedures for measurement cumbersome. Also, the need for separate
equipment increases the scale of the overall measurement
apparatus.
[0005] On the other hand, there are known biosensors using a
detection method different from that using detection elements such
as surface acoustic wave devices. A reagent including an enzyme or
the like is coated on a measurement electrode, the specimen is made
to react with that portion, and change in current at the
measurement electrode is read (see PTL 4).
[0006] PTL 4 discloses a technique in which the biosensor itself
can suction specimens by capillary action. A slender specimen
supply channel is extended to the portion of the measurement
electrode where the reagent is coated and the specimen is suctioned
to the portion electrode where the reagent is coated by capillary
action.
[0007] Note that the method to measure specimens by coating the
measurement electrode with a reagent including an enzyme or the
like as in PTL 4 is limited in test items which can be measured,
and accordingly is inconvenient in cases where testing of multiple
items is desired.
[0008] Now, the structure of the measurement portion of the
biosensor described in PTL 4 is one where a reagent is coated on
the electrode, so the thickness of the measurement portion is that
of the electrode, which is very thin. Accordingly, the slender
specimen supply channel can be led up to the measurement portion
without the specimen supply channel being blocked partway
though.
[0009] On the other hand, detecting devices of biosensors using
detection elements such as surface acoustic wave devices are formed
using piezoelectric substrates or the like, so the detection
element has a certain thickness. Accordingly, if the technique in
PTL 4 is applied, the specimen supply channel will be blocked by
the detection element, so feeding the specimen solution to the
detection unit is difficult.
[0010] Accordingly, it has been found desirable to provide a
biosensor including a suctioning mechanism, even in a case of using
a thick detection element such as a surface acoustic wave
device.
CITATION LIST
Patent Literature
[0011] PTL 1: Japanese Unexamined Patent Application Publication
No. 5-240762
[0012] PTL 2: Japanese Unexamined Patent Application Publication
No. 2006-184011
[0013] PTL 3: Japanese Unexamined Patent Application Publication
No. 2010-239477
[0014] PTL 4: Japanese Unexamined Patent Application Publication
No. 2005-249491
SUMMARY OF INVENTION
[0015] A biosensor according to one aspect of the present invention
includes: a first cover member including an element-accommodating
recess in an upper face thereof; a detection element including an
element substrate accommodated in the element-accommodating recess,
and at least one detection unit situated on the upper face of the
element substrate to perform detection of an analyte; and a second
cover member joined to the first cover and covering the detection
element. The second cover member includes an inflow port from which
the analyte flows in and a groove extending from the inflow port to
at least above the detection unit.
[0016] A biosensor according to one aspect of the present invention
includes: a mounting member including an inflow port into which an
analyte flows in, at an end thereof, and a groove connected to the
inflow port on an upper face thereof; a detection element including
at least one detection unit situated on a principal face to perform
detection of the analyte, mounted on the mounting member with the
detection unit being situated above the groove in a state of the
principal face facing the upper face of the mounting member; and a
cover member including an element-accommodating recess on a lower
face thereof. The cover member is joined to the mounting member and
accommodates the detection element in the element-accommodating
recess.
[0017] Also, a biosensor according to one aspect of the present
invention includes: a cover member including an inflow port for an
analyte, a groove-shaped channel connected to the inflow port, and
a recessed space connected to the channel; and a detection element
including a element substrate accommodated in the space, and a
detection unit situated on an upper face of the element substrate
and reacting with a component included in the analyte.
[0018] According to the biosensor, accommodating the detection
element in the element-accommodating recess allows a channel of
analyte solution to be secured from the inflow port to the
detection unit, and analyte solution suctioned from the inflow port
by capillary action or the like can be fed to the detection unit,
even in a case of using a thick detection element. That is to say,
a biosensor can be provided which is easy to use for measurement
work, having a suctioning mechanism for analyte solution itself
while using a thick detection element.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a perspective view of a biosensor according to a
first embodiment of the present invention.
[0020] FIG. 2 is an exploded perspective view of a first cover
member and a second cover member.
[0021] FIG. 3 is a perspective view of the biosensor illustrated in
FIG. 1, in a state of a fourth board removed.
[0022] FIG. 4(a) is a cross-sectional view along IVa-IVa' in FIG.
1, and FIG. 4(b) is a cross-sectional view along IVb-IVb' in FIG.
1.
[0023] FIG. 5 is a perspective view of a detection element used in
the biosensor illustrated in FIG. 1.
[0024] FIG. 6 is a plan view of the detection element illustrated
in FIG. 5 in a state with a first protective member and a second
protective member removed.
[0025] FIG. 7 is a cross-sectional view illustrating a modification
of a biosensor according to an embodiment of the present
invention.
[0026] FIG. 8 is a cross-sectional view illustrating another
modification of a biosensor according to an embodiment of the
present invention.
[0027] FIGS. 9(a), 9(b) and 9(c) are cross-sectional views
illustrating an example of a biosensor where a hydrophilic film has
been attached to a channel.
[0028] FIG. 10 is an exploded perspective view of a mounting member
and cover member used in a biosensor according to a second
embodiment of the present invention.
[0029] FIGS. 11(a) and 11(b) are cross-sectional views of the
biosensor according to the second embodiment, where FIG. 11(a) is a
cross-sectional view corresponding to FIG. 4(a), and FIG. 11(b) is
a cross-sectional view corresponding to FIG. 4(b).
[0030] FIG. 12 is an exploded perspective view of a biosensor
according to a third embodiment of the present invention.
[0031] FIG. 13(a) is a perspective view of the biosensor
illustrated in FIG. 12 in a state with the second cover member and
an assisting board omitted, FIG. 13(b) is a perspective view of the
biosensor illustrated in FIG. 12 in a state with the second cover
member omitted, and FIG. 13(c) is a perspective view of the
biosensor illustrated in FIG. 12 in a state with the fourth board
omitted.
[0032] FIGS. 14(a) and 14(b) are cross-sectional views of the
biosensor illustrated in FIG. 12, where FIG. 14(a) is a
cross-sectional view of the portion corresponding to FIG. 4(a), and
FIG. 14(b) is a cross-sectional view of the portion corresponding
to FIG. 4(b).
[0033] FIG. 15 is a perspective view of a detection element used in
the biosensor illustrated in FIG. 12.
[0034] FIG. 16 is a cross-sectional view illustrating a
modification of the biosensor illustrated in FIG. 12.
[0035] FIG. 17 is a perspective view of a detection element used in
the biosensor illustrated in FIG. 16.
[0036] FIG. 18 is an exploded perspective view of a biosensor
according to a fourth embodiment of the present invention.
[0037] FIG. 19(a) is a perspective view of the biosensor
illustrated in FIG. 18 in a state with the second cover member and
assisting board omitted, FIG. 19(b) is a perspective view of the
biosensor illustrated in FIG. 18 in a state with the second cover
member omitted, and FIG. 19(c) is a perspective view of the
biosensor illustrated in FIG. 18 in a state with a third board
omitted.
[0038] FIGS. 20(a) and 20(b) are cross-sectional views of the
biosensor illustrated in FIG. 18, where FIG. 20(a) is a
cross-sectional view of the portion corresponding to FIG. 4(a), and
FIG. 20(b) is a cross-sectional view of the portion corresponding
to FIG. 4(b).
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0039] Embodiments of the biosensor according to the present
invention will be described in detail with reference to the
drawings. Note that components which are the same in the drawings
described below are denoted with the same reference numerals. The
sizes of the members and distances among the members are
illustrated schematically, and may be different from actual sizes
and distances.
[0040] Either side of the biosensor 100 may be up or down, but for
sake of description in the following, an orthogonal coordinates
system xyz is defined, and terms such as "upper face" and "lower
face" are used with the positive side of the z direction being
up.
First Embodiment
[0041] The biosensor 100 primarily includes a first cover member 1,
a second cover member 2, and a detection element 3. The first cover
member 1 includes a first board 1a and a second board 1b layered
upon the first board 1a, and the second cover member 2 includes a
third board 2a layered upon the second board 1b and a fourth board
2b layered upon the third board 2a. The detection element 3 is a
surface acoustic wave device which primarily includes an element
substrate 10, a first IDT (InterDigital Transducer) electrode 11, a
second IDT electrode 12, and detection units 13 (see FIG. 5).
[0042] The first cover member 1 and second cover member 2 are
applied to each other, and the detection element 3 is accommodated
within the first cover member 1 and second cover member 2. The
first cover member 1 has an element-accommodating recess 5 on the
upper face thereof, with the detection element 3 situated in the
element-accommodating recess 5, as illustrated in the
cross-sectional views in FIG. 4.
[0043] The an inflow port 14, through which the specimen solution
enters, is formed at the edge of the second cover member 2 in the
longitudinal direction (x direction), as illustrated in FIG. 1. A
groove 15 extending from the inflow port 14 toward a portion
directly above the detection element 3 is also formed in the second
cover member 2. The groove 15 is illustrated by dotted lines in
FIG. 1 to indicate the position thereof.
[0044] FIG. 2 illustrates an exploded perspective view of the first
cover member 1 and second cover member 2.
[0045] The first board 1a included in the first cover member 1 is
formed as a flat plate, 0.1 mm to 0.5 mm thick, for example. The
planar shape of the first board 1a is generally rectangular, but
one end in the longitudinal direction is an arc shape protruding
outwards. The length of the first board 1a in the x direction is 1
cm to 5 cm, and the length in the y direction is 1 cm to 3 cm, for
example.
[0046] The second board 1b is bonded onto the upper face of the
first board 1a. The second board 1b is in the form of a flat plate
frame, formed by a recess-forming through hole 4 having been formed
in a flat plate frame form. The thickness thereof is 0.1 mm to 0.5
mm, for example. The outer form thereof in planar view is
approximately the same as that of the first board 1a, and the
x-directional length and y-directional length are also
approximately the same as those of the first board 1a.
[0047] Joining the second board 1b to which the recess-forming
through hole 4 has been formed, to the first board 1a, forms the
element-accommodating recess 5 in the first cover member 1 of the
flat plate form. That is to say, the upper face of the first board
1a situated within the recess-forming through hole 4 serves as the
bottom face of the element-accommodating recess 5, and the inner
walls of the recess-forming through hole 4 serve as the inner walls
of the element-accommodating recess 5.
[0048] Terminals 6, and wiring 7 laid from the terminals 6 to the
recess-forming through hole 4, are formed on the upper face of the
second board 1b. The terminals 6 are formed at the other end of the
second board 1b in the x direction on the upper face thereof. When
the biosensor 100 is inserted into an external measurement
instrument (not illustrated), the portion where the terminals 6 are
formed is the portion actually inserted thereto. The terminals 6
are to be electrically connected to the external measurement
instrument. Also, the terminals 6 and detection element 3 are
electrically connected by the wiring 7 and so forth. Signals are
input to the biosensor 100 from the external measurement instrument
via the terminals 6, and signals from the biosensor 100 are output
to the external measurement instrument via the terminals 6.
[0049] The second cover member 2 is joined to the upper face of the
first cover member 1 made up of the first board 1a and second board
1b. The second cover member 2 includes the third board 2a and
fourth board 2b.
[0050] The third board 2a is bonded to the upper face of the second
board 1b. The third board 2a is formed as a flat plate, 0.1 mm to
0.5 mm thick, for example. The planar shape of the second board 2a
is generally rectangular, but one end in the longitudinal direction
is an arc shape protruding outwards, in the same way as with the
first board 1a and second board 1b. The length of the third board
2a in the x direction is somewhat shorter than the length of the
second board 1b in the x direction, 0.8 mm to 4.8 cm, for example,
so that the terminals 6 on the second board 1b will be exposed. The
length in the y direction is 1 cm to 3 cm, for example, the same as
with the first board 1a and second board 1b.
[0051] A notch 8 is formed in the third board 2a. The notch 8 is a
portion formed by notching out the third board 2a from the tip of
the arc-shaped one end toward the other end in the x direction. The
notch 8 penetrates the third board 2a in the thickness direction.
This notch 8 is to form the groove 15. A first through hole 16 and
a second through hole 17 which penetrate the third board 2a in the
thickness direction are formed on either side of the notch 8 in the
third board 2a. The arrangement is such that the connection portion
between the detection element 3 and wiring 7 is situated within the
first through hole 16 and second through hole 17 when layering the
third board 2a on the second board 1b. The portion between the
first through hole 16 and notch 8 of the third board 2a serves as a
first partition 25 partitioning between the groove 15 and the space
formed by the first through hole 16, which will be described later.
Also, the portion between the second through hole 17 and notch 8 of
the third board 2a serves as a second partition 26 partitioning
between the groove 15 and the space formed by the second through
hole 17.
[0052] The fourth board 2b is bonded onto the upper face of the
third board 2a. The fourth board 2b is in the form of a flat plate,
and the thickness thereof is 0.1 mm to 0.5 mm, for example. The
outer form thereof in planar view is approximately the same as that
of the third board 2a, and the x-directional length and
y-directional length are also approximately the same as those of
the third board 2a. Bonding the fourth board 2b onto the third
board 2a where the notch 8 has been formed forms the groove 15 on
the lower face of the second cover member 2. That is to say, the
lower face of the fourth board 2b situated within the notch 8
serves as the bottom face of the groove 15, and the inner walls of
the notch 8 are the inner walls of the groove 15. The groove 15
extends from the inflow port 14 to at least a region directly above
the detection units 13. The cross-sectional shape thereof is
rectangular, for example.
[0053] A vent hole 18 penetrating the fourth board 2b in the
thickness direction is formed in the fourth board 2b. The vent hole
18 is situated at the end portion of the notch 8 when the fourth
board 2b is layered on the third board 2a. Accordingly, the end of
the groove 15 is connected with the vent hole 18. This vent hole 18
serves to externally discharge air and the like that is in the
groove 15.
[0054] The vent hole 18 may be of any shape, such as a cylinder,
square pillar, or the like, as long as air within the channel can
be removed. However, if the planar shape of the vent hole 18 is too
great, the area of analyte solution field in the channel coming
into contact with external air also increases, and moisture tends
to evaporate from the analyte solution. This readily leads to
change in concentration of the analyte solution, incurring
deterioration in measurement precision. Accordingly, the planar
shape of the vent hole 18 is made to be no larger than necessary.
Specifically, in a case where the vent hole 18 is formed as a
cylinder, the diameter is made to be 1 mm or smaller, and in a case
where the vent hole 18 is formed as a square pillar, the length of
each side is made to be 1 mm or smaller.
[0055] The inner walls of the vent hole 18 are hydrophobic. This
prevents the analyte solution filling the channel from leaking out
from the vent hole 18.
[0056] The first board 1a, second board 1b, third board 2a, and
fourth board 2b are formed of paper, plastic, celluloid, ceramic,
or the like, for example. These boards may all be formed of the
same material. Forming the boards all of the same material enables
the thermal expansion coefficients of the boards to be made
approximately uniform, thereby suppressing deformation due to
difference in thermal expansion coefficients among the boards.
Also, the detection units 13 may be coated with biological
materials, some of which are altered by external light such as
ultraviolet rays. In this case, a non-transparent material having
light-shielding properties is preferably used as the material for
the first cover member 1 and second cover member 2. On the other
hand, in cases where there is hardly any alteration at the
detection units 13 due to external light, the second cover member 2
where the groove 15 is formed may be formed of a material close to
transparent. This allows of visual inspection of the analyte
solution flowing through the channel.
[0057] Next, the detection element 3 will be described in detail.
FIG. 5 is a perspective view of the detection element 3, and FIG. 6
is a plan view of the detection element 3 in a state with a first
protective member 21 and a second protective member 22 removed.
[0058] The detection element 3 includes the element substrate 10,
and the detection units 13, first IDT electrodes 11, second IDT
electrodes 12, and first extracting electrodes 19 and second
extracting electrodes 20, disposed upon the upper face of the
element substrate 10.
[0059] The element substrate 10 is a monocrystal substrate having
piezoelectric properties, such as a lithium tantalite (LiTaO.sub.3)
monocrystal, a lithium niobate (LiNbO.sub.3) monocrystal, or
crystal, for example. The planar shape and dimensions of the
element substrate 10 may be set as appropriate. One example of the
thickness of the element substrate 10 is 0.3 mm to 1 mm.
[0060] The first IDT electrodes 11 include a pair of toothcomb
electrodes, as illustrated in FIG. 6. The toothcomb electrodes
include two bus bars, and multiple electrode fingers extending from
each bus bar towards the other bus bar. Each pair of toothcomb
electrodes is situated such that the multiple electrode fingers
mesh with each other. The second IDT electrodes 12 are also
configured in the same way as the first IDT electrodes 11. The
first IDT electrodes 11 and second IDT electrodes 12 make
transversal IDT electrodes.
[0061] The first IDT electrodes 11 are for generating a
predetermined surface acoustic wave (SAW), and the second IDT
electrodes 12 are for receiving the SAWs generated at the first IDT
electrodes 11. The first IDT electrodes 11 and second IDT
electrodes 12 are disposed on the same straight line so that SAWs
generated at the first IDT electrodes 11 can be received at the
second IDT electrodes 12. Frequency properties can be designed
using parameters such as the number of electrode fingers of the
first IDT electrodes 11 and second IDT electrodes 12, distance
between adjacent electrode fingers, intersection width of the
electrode fingers, and so forth. While there are various vibration
modes for SAWs excited by the IDT electrodes, The detection element
3 employs a vibration mode of transverse waves called SH waves, for
example.
[0062] Also, an elastic material may be provided to the outer side
of the first IDT electrodes 11 and second IDT electrodes 12 in the
direction of propagation of SAWs (y direction), to suppress
reflection of the SAWs. The SAW frequency can be set within a range
of several megahertz (MHz) to several gigahertz (GHz).
Particularly, setting the SAW frequency to several hundred MHz to 2
GHz is practical, and enables reduction in size of the detection
element 3 to be realized, thereby realizing reduction in size of
the biosensor 100.
[0063] The first IDT electrodes 11 are connected with first
extracting electrodes 19. The first extracting electrodes 19 are
extracted from the first IDT electrodes 11 in the direction
opposite to the detection units 13, and ends 19e of the first
extracting electrodes 19 are electrically connected with the wiring
7 on the first cover member 1. The second IDT electrodes 12 are
similarly connected with second extracting electrodes 20. The
second extracting electrodes 20 are extracted from the second IDT
electrodes 12 in the direction opposite to the detection units 13,
and ends 20e of the second extracting electrodes 20 are
electrically connected with the wiring 7.
[0064] The first IDT electrodes 11, second IDT electrodes 12, first
extracting electrodes 19, and second extracting electrodes 20, are
made of aluminum, an alloy of aluminum and copper, or the like, for
example. These electrodes may be of a multi-layer structure. In a
case of employing a multi-layer structure, the first layer is made
of titanium or chromium, and the second layer is of aluminum or
aluminum alloy, for example.
[0065] The first IDT electrodes 11 and second IDT electrodes 12 are
covered by a protective film (not illustrated). The protective film
is to contribute to prevention of oxidization of the first IDT
electrodes 11 and second IDT electrodes 12. The protective film is
formed of, for example, silicon oxide, aluminum oxide, zinc oxide,
titanium oxide, silicon nitride, or silicon. The thickness of the
protective film is, for example, around 1/10 of the thickness of
the first IDT electrodes 11 and second IDT electrodes 12 (10 to 30
nm). The protective film may be formed over the entire upper face
of the element substrate 10, leaving the ends 19e of the first
extracting electrodes 19 and the ends 20e of the second extracting
electrodes 20 exposed.
[0066] The detection units 13 are situated between the first IDT
electrodes 11 and second IDT electrodes 12. The detection units 13
are formed of, for example, metal film, and an aptamer made up of a
nucleic acid or peptide fixed to the surface of the metal film. The
metal film has a two-layered structure of chromium and a gold film
formed on the chromium, for example. The detection units 13 are for
causing a reaction with the target matter in the analyte solution.
Specifically, upon the analyte solution coming into contact with
the detection units 13, a particular target matter within the
analyte solution binds to the aptamer corresponding to that target
matter.
[0067] Taking a first IDT electrode, second IDT electrode, and
detection unit 13, disposed in the y direction as one set, the
biosensor 100 includes two of these sets. Thus, two types of
detection can be performed with a single biosensor, by making the
target matter reacting at one detection unit 13 to be different
from the target matter reacting at the other detection unit 13.
[0068] The first IDT electrodes 11 are covered by the first
protective member 21 as illustrated in FIG. 5. The first protective
member 21 is situated on the upper face of the element substrate
10, and has a first recess 51 opening toward the upward face side
of the element substrate 10, as illustrated in FIG. 4(a). A region
surrounded by the inner face of the first recess 51 and the upper
face of the element substrate 10 in a state of the first protective
member 21 being placed on the upper face of the element substrate
10 is a first vibration space 23. The first IDT electrodes 11 are
sealed within the first vibration space 23. Accordingly, the first
IDT electrodes 11 are, isolated from the external air and analyte
solution, and thus the first IDT electrodes 11 can be protected.
Also, deterioration of properties of the SAWs excited by the first
IDT electrodes 11 can be suppressed by securing the first vibration
space 23.
[0069] Similarly, the second IDT electrode 12 are covered by the
second protective member 22. The second protective member 22 is
situated on the upper face of the element substrate 10, and has a
second recess 52 opening toward the upward face side of the element
substrate 10, as illustrated in FIG. 4(a). A region surrounded by
the inner face of the second recess 52 and the upper face of the
element substrate 10 in a state of the second protective member 22
being placed on the upper face of the element substrate 10 is a
second vibration space 24. The second IDT electrodes 12 are sealed
within the second vibration space 24. Accordingly, the second IDT
electrodes 12 are isolated from the external air and analyte
solution, and thus the second IDT electrodes 12 can be protected.
Also, deterioration of properties of the SAWs received by the
second IDT electrode 12 can be suppressed by securing the second
vibration space 24.
[0070] The first protective member 21 includes a ring-shaped frame
fixed on the upper face of the element substrate 10 so as to
surround the two first IDT electrodes 11 disposed in the x
direction, and a lid fixed to the frame so as to seal the opening
of the frame. This sort of structure can be formed by, for example,
forming a resin film using photosensitive resin material and
patterning this resin film by photolithography or the like. The
second protective member 21 can also be formed in the same way.
[0071] Note that one first protective member 23 is covering two
first IDT electrodes 11 in the biosensor 100, but an arrangement
may be made where the two first IDT electrodes 11 are each covered
by individual first protective members 23. Alternatively, the two
first IDT electrodes 11 may be covered with one first protective
member 23, and a partition disposed between the two first IDT
electrodes 11. Similarly in the case of the second IDT electrodes
12, two second IDT electrodes 12 may be each covered by individual
second protective members 24, or one second vibration space 24 may
be used and a partition disposed between the two second IDT
electrodes 12.
[0072] Detection of a analyte solution at the detection elements 3
using SAWs is performed as follows. First, a predetermined voltage
is applied to the first IDT electrodes 11 from an external
measuring instrument, via the wiring 7, first extracting electrodes
19, and so forth. The surface of the element substrate 10 is thus
excited in the formation region of the first IDT electrodes 11, and
a SAW having a predetermined frequency is generated. A part of the
generated SAW is propagated toward the detection unit 13, passes
through the detection unit 13, and then reaches the second IDT
electrode 12. At the detection unit 13, the aptamer of the
detection unit 13 has bound to the particular target matter in the
analyte solution, so the weight of the detection unit 13 has
increased by an amount equivalent to the amount of binding.
Accordingly, properties of the SAW passing underneath the detection
unit 13, such as phase, change. The SAW of which the properties
have changed reach the second IDT electrode, whereupon
corresponding voltage is generated at the second IDT electrode.
This voltage is externally output via the second extracting
electrode 20, wiring 7, and so forth, and read at the external
measurement instrument, whereby the properties and components of
the analyte solution can be found.
[0073] The biosensor 100 employs capillary action to guide the
analyte solution to the detection unit 13. Specifically, joining
the second cover member 2 to the first cover member 1 makes the
portion of the groove 15 on the lower face of the second cover
member 2 to become a slender tube. Capillary action can thus be
made to occur at the slender tube formed by the groove 15, by
setting the width, diameter, or the like of the groove 15 to
predetermined values, taking into consideration the type of analyte
solution, the material of the first cover member 1 and second cover
member 2, and so forth. The width of the groove 15 (y-dimensional
dimension) is, for example, 0.5 mm to 3 mm, and the depth
(z-directional dimension) is, for example, 0.1 mm to 0.5 mm. The
groove 15 also includes an extended portion 15e which extends
beyond the detection unit 13. The second cover member 2 includes
the vent hole 18 which is connected to the extended portion 15e.
When the analyte solution enters the channel, air which had been
present in the channel is vented out from the vent hole 18.
[0074] The tube which exhibits such capillary action is formed by
the cover members first cover member 1 and second cover member 2.
Thus, when the inflow port 14 is brought into contact with the
analyte solution, the analyte solution is suctioned into within the
cover members with the groove 15 as a channel. Accordingly, the
biosensor 100 itself has a analyte solution suctioning mechanism,
so suctioning of analyte solution can be performed without using an
instrument such as a pipette. Also, the portion where the inflow
port 14 is formed is rounded and the inflow port 14 is formed at
the tip thereof, so the inflow port 14 can be readily
discerned.
[0075] Part or all of the inner face of the channel of the
biosensor 100, for example the bottom face of the groove 15, the
walls of the groove 15, and so forth, are hydrophilic. Hydrophilic
inner faces of the channel facilitate capillary action, so the
analyte solution is more readily suctioned from the inflow port 14.
The portion of the inner faces of the channel which are hydrophilic
have an angle of contact of 60.degree. or less as to water. An
angle of contact of 60.degree. or less causes capillary action more
readily, and suction of the analyte solution into the inflow port
occurs in a more sure manner when bringing the analyte solution
into contact with the inflow port.
[0076] Conceivable methods to render the inner faces of the groove
15 hydrophilic include a method of subjecting the inner faces of
the groove 15 to hydrophilicity induction processing, a method of
applying a hydrophilic film on the inner faces of the groove 15, a
method of forming the second cover member 2 configuring the groove
15 of a hydrophilic material, and so forth.
[0077] Of these, the method of subjecting the inner faces of the
groove 15 to hydrophilicity induction processing, and the method of
applying a hydrophilic film on the inner faces of the groove 15
cause the analyte solution to flow through the channel following
the hydrophilic portions. Accordingly, almost all of the analyte
solution flows through the channel, and flow of the analyte
solution to unintended portions is suppressed, so highly precise
measurement can be realized. Also, capillary action can be caused
with these methods even if the cover members are formed of
hydrophobic material. This is advantageous in that there are more
options of materials which can be selected for the cover
members.
[0078] The inner faces of the groove 15 may be subjected to
hydrophilicity induction processing by, for example, asking the
inner faces of the groove 15 by oxygen plasma, then coating with a
silane coupling agent, and finally coupling with polyethylene
glycol. Alternatively, the surface of inner faces of the groove 15
may be treated using a treatment agent including
phosphorylcholine.
[0079] Also, a commercially-available polyester film or
polyethylene film treated by hydrophilicity induction processing,
or the like, may be used as the hydrophilic film. FIG. 9
illustrates examples of a hydrophilic film 34 applied to the
channel. FIG. 9(a) and FIG. 9(b) are cross-sectional views
corresponding to FIG. 4(a), and FIG. 9(c) is a cross-sectional view
corresponding to FIG. 4(b). The film 34 may be formed to just the
upper face of the channel, that is the bottom face of the groove
15, as illustrated in FIG. 9(a), or may be formed to just the side
faces of the channel, that is the walls of the groove 15, as
illustrated in FIG. 9(b). Alternatively, the film 34 may be formed
to the lower face of the channel as illustrated in FIG. 9(c), or a
combination of these FIG. 9(a) through FIG. 9(c) may be used.
[0080] Now, the depth of the analyte solution channel formed by the
groove 15 is around 0.3 mm, and the thickness of the detection
element 3 is around 0.3 mm, so the depth of the channel and the
thickness of the detection element 3 are approximately equal.
Accordingly, placing the detection element 3 on the channel in the
state blocks off the channel. Thus, the biosensor 100 includes an
element-accommodating recess 5 on the first cover member 1 where
the detection element 3 is mounted, and the detection element 3 is
stored in this element-accommodating recess 5, so as to prevent the
analyte solution channel from being blocked, as illustrated in FIG.
4. That is, the depth of the element-accommodating recess 5 is made
to be around the same as the thickness of the detection element 3,
and the detection element 3 is mounted within the
element-accommodating recess 5, thereby securing the channel formed
by the groove 15.
[0081] FIG. 3 is a perspective view illustrating a state where the
fourth board 2b of the second cover member 2 has been removed. The
analyte solution channel is secured, so the analyte solution
flowing into the channel by capillary action can be smoothly guided
to the detection unit 13.
[0082] The height of the upper face of the element substrate 10
from the bottom face of the element-accommodating recess 5 is
preferably the same or smaller (lower) than the depth of the
element-accommodating recess 5 as illustrated in FIG. 4, from the
perspective of sufficiently securing the analyte solution channel.
For example, an arrangement where the height of the upper face of
the element substrate 10 from the bottom face of the
element-accommodating recess 5 and the depth of the
element-accommodating recess 5 are the same enables the bottom face
of the channel and the detection unit 13 to be on approximately the
same height, when viewing the inside of the groove 15 from the
inflow port 14. The biosensor 100 is arranged such that the
thickness of the element substrate 10 is smaller (thinner) than the
depth of the element-accommodating recess 5, so that the height of
the upper faces of the first protective member 21 and second
protective member 22 from the bottom face of the
element-accommodating recess 5 is approximately the same as the
depth of the element-accommodating recess 5. If the height of the
first protective member 21 and second protective member 22 from the
bottom face of the element-accommodating recess 5 is greater
(higher) than the depth of the element-accommodating recess 5, the
first partition 25 and second partition 26 of the third board 2a
will have to be worked so as to be thinner than the other portions.
However, arranging so that the height of the first protective
member 21 and second protective member 22 from the bottom face of
the element-accommodating recess 5 is approximately the same as the
depth of the element-accommodating recess 5 does away with the need
for such working, facilitating production efficiency.
[0083] The planar shape of the element-accommodating recess 5 is,
for example, a similar shape to the planar shape of the element
substrate 10, and the element-accommodating recess 5 is somewhat
larger than the element substrate 10. Specifically, the size of the
element-accommodating recess 5 is such that when the element
substrate 10 is mounted to the element-accommodating recess 5,
there is formed a gap of around 100 .mu.m between the side faces of
the element substrate 10 and the inner walls of the
element-accommodating recess 5.
[0084] The detection element 3 is fixed to the bottom face of the
element-accommodating recess 5 by a die bond including, for
example, epoxy resin, polyimide resin, silicon resin, or the like,
as a primary component thereof. The ends 19e of the first
extracting electrodes 19 and the wiring 7 are electrically
connected by fine metal wires 27 formed of Au or the like, for
example. This is the same for the connection between the ends 20e
of the second extracting electrodes 20 and the wiring 7. Note that
the connection of the first extracting electrodes 19 and second
extracting electrodes 20 to the wiring 7 is not restricted to
connection by the fine metal wires 27, and an electroconductive
adhesive agent such as Ag paste or the like may be used, for
example.
[0085] Spaces are formed at the connection portion of the first
extracting electrodes 19 and second extracting electrodes 20 to the
wiring 7 so damage to the fine metal wires 27 at the time of
bonding the second cover member 2 to the first cover member 1 is
suppressed. These spaces can be easily formed by forming the first
through hole 16 and second through hole 17 in the third board 2a
beforehand. The existence of the first partition 25 between the
first through hole 16 and the groove 15 can suppress the analyte
solution flowing through the groove 15 from flowing into the spaces
formed by the first through hole 16. Accordingly, short-circuiting
between the multiple first extracting electrodes 19 due to the
analyte solution can be suppressed. In the same way, the existence
of the second partition 26 between the second through hole 17 and
the groove 15 can suppress the analyte solution flowing through the
groove 15 from flowing into the spaces formed by the second through
hole 17. Accordingly, short-circuiting between the multiple second
extracting electrode 20 due to the analyte solution can be
suppressed.
[0086] The first partition 25 is situated above the first
protective member 21, and the second partition 26 is situated above
the second protective member 22. Accordingly, the analyte solution
channel is defined by not only the groove 15 but also by the side
walls of the first protective member 21 and the side walls of the
second protective member 22. From the perspective of preventing
leakage of the analyte solution to the spaces formed by the first
through hole 16 and second through hole 17, the first partition 25
preferably comes into contact with the upper face of the first
protective member 21 and the second partition 26 with the upper
face of the first protective member 22. However, the biosensor 100
is configured such that gaps are formed between the lower face of
the first partition 25 and upper face of the first protective
member 21, and between the lower face of the second partition 26
and the upper face of the second protective member 22. The gap is
10 .mu.m to 60 .mu.m, for example. Providing these gaps enables
pressure applied to this portion when gripping the biosensor 100
between fingers to by absorbed at the gaps, thereby suppressing
pressure from being directly applied to the first protective member
21 and second protective member 22. As a result, the first
vibration space 23 and second vibration space 24 can be kept from
greatly deforming. Also, analyte solutions normally have a certain
level of viscoelasticity, so forming the gaps to be 10 .mu.m to 60
.mu.m makes it difficult for the analyte solution to enter the
gaps, and leakage of the analyte solution to the gaps formed by the
first through hole 16 and second through hole 17 can be
suppressed.
[0087] The width of the first partition 25 is formed wider than the
width of the first vibration space 23. In other words, the side
wall of the first partition 25 is situated on the frame of the
first protective member 21. Accordingly, even in a case where the
first partition 25 comes into contact with the first hollow portion
21 due to external pressure, the first partition 25 is supported by
the frame, so deformation of the first protective member 21 can be
suppressed. Due to the same reason, the width of the second
partition 26 is also preferably wider than the width of the first
vibration space 25.
[0088] The first extracting electrodes 19, second extracting
electrodes 20, fine metal wires 27, and wiring 7, within the spaces
formed by the first through hole 16 and second through hole 17, are
covered by an insulating member 28. Covering the first extracting
electrodes 19, second extracting electrodes 20, fine metal wires
27, and wiring 7 by the insulating member 28 can suppress corrosion
of these electrodes and the like. Also, providing the insulating
member 27 enables the analyte solution to be held back by the
insulating member 27 even if the analyte solution does enter into
the gap between the first partition 25 and first protective member
21 or the gap between the second partition 26 and second protective
member 22. Thus, short-circuiting between extracting electrodes due
to leaking analyte solution can be suppressed.
[0089] Thus, according to the biosensor 100, the analyte solution
channel from the inflow port 14 to the detection units 13 can be
secured due to having accommodated the detection element 3 in the
element-accommodating recess 5 in the first cover member 1, and the
analyte solution suctioned by capillary action and so forth from
the inflow port can be fed to the detection units 13. That is to
say, a biosensor 100 including a suction mechanism in itself, and
which uses a thick detection element 3, can be provided.
[0090] FIG. 7 is a cross-sectional view illustrating a modification
of the biosensor 100. This cross-sectional view corresponds to the
cross-section in FIG. 4(a).
[0091] The position where the terminals 6 are formed has been
changed with this modification. While the terminals 6 are formed at
the other end of the second board 1b in the longitudinal direction
in the above-described embodiment, the terminals 6 are formed on
the upper face of the fourth board 2b in this modification. The
terminals 6 and wiring 7 are electrically connected by through
conductors 29 penetrating the second cover member 2. The through
conductors 29 are formed of Ag paste, plating, or the like, for
example. The terminals 6 may also be formed on the lower face side
of the first cover member 1. Accordingly, the terminals 6 can be
formed at optional positions on the first cover member 1 and second
cover member 2, and the positions can be decided in accordance with
the measurement instrument being used.
[0092] FIG. 8 is a cross-sectional view illustrating another
modification of the biosensor 100. This cross-sectional view
corresponds to the cross-section in FIG. 4(b).
[0093] This modification includes a suctioning member 30 to suction
the analyte solution at a predetermined speed. The suctioning
member 30 is provided at the far end of the channel formed by the
groove 15. This suctioning member 30 suctions excess analyte
solution and makes the amount of analyte solution flowing over the
detection unit 13 to be constant, so stable measurement can be
performed. The suctioning member 30 is formed of a porous material
such as sponge which can suction liquid, for example.
Second Embodiment
[0094] Next, a biosensor 200 according to a second embodiment will
be described with reference to FIG. 10 and FIG. 11. FIG. 10 is an
exploded perspective view of a mounting member 31 and a cover
member 32 used in the biosensor 200. FIG. 11 is a cross-sectional
view, with FIG. 11(a) and FIG. 11(b) being cross-sections
corresponding to FIG. 4(a) and FIG. 4(b), respectively.
[0095] The biosensor 200 differs from the biosensor 100 according
to the first embodiment described above primarily with regard to
the form of the cover member and the method of mounting the
detection element 3.
[0096] Specifically, the lower face of the detection element 3 is
mounted to the first cover member 1 with the face of the detection
element 3 on which the detection units 13 and first and second IDT
electrodes 11 and 12 are formed facing upwards (z direction) in the
biosensor 100 according to the first embodiment. On the other hand,
the detection element 3 is mounted to the mounting member 31 with
the face on which the detection units 13 and first and second IDT
electrodes 11 and 12 are formed facing downwards (-z direction) in
the biosensor 200. That is to say, the detection element 3 of the
biosensor 200 is mounted face down.
[0097] The detection element 3 can be mounted face down by, for
example, joining the ends 19e of the first extracting electrodes 19
on the element substrate 3 to ends 7e of the wiring 7 on the
mounting member 31 by an electroconductive joining material 33 such
as solder, and similarly joining the ends 20e of the second
extracting electrodes 20 on the element substrate 3 to ends 7e of
the wiring 7 on the mounting member 31 by the electroconductive
joining material 33 such as solder. Joining may also be performed
by electroconductive bumps of Au or the like, for example, besides
such a joining method using solder.
[0098] In the face-up mounting of the detection element 3 as with
the biosensor 100 according to the first embodiment, mechanical
connection between the detection element 3 and the first cover
member 1 is performed by the die bond material introduced between
the lower face of the element substrate 3 and the
element-accommodating recess, and electrical connection between the
element substrate 3 and the first cover member 1 is performed by
the fine metal wires 27. That is to say, mechanical connection and
electrical joining are performed separately.
[0099] On the other hand, face-down mounting of the detection
element 3 as with the biosensor 200 enables mechanical joining and
electrical joining of the detection element 3 and mounting member
31 to be performed at the same time, so manufacturing efficiency is
good.
[0100] The shape of the cover member of the biosensor 200 differs
from that of the biosensor 100 according to the first embodiment as
well. The biosensor 100 according to the first embodiment is
configured such that, of the first cover member 1 and second cover
member 2, the first cover member 1 which is disposed below is
provided with the element-accommodating recess 5, and the detection
element 3 is accommodated in this element-accommodating recess 5.
Thus, the channel is guided to the detection units 13 without being
blocked off by the detection element 3. Conversely, with the
biosensor 200 as illustrated in FIG. 11, the element-accommodating
recess 5 is provided to, of the mounting member 31 and cover member
32, the lower face of the cover member 1 disposed above, so that
the detection element 3 is accommodated in this
element-accommodating recess 5. Accordingly, a channel guided to
the region below the detection units 13 can be secured while
accommodating the thick detection element 3 within a cover
member.
[0101] The mounting member 31 includes a fifth board 31a and sixth
board 31b, and the cover member 32 includes a seventh board 32a and
eighth board 32b, as illustrated in FIG. 10.
[0102] The fifth board 31a is formed as a flat plate, and basically
is the same as the first board 1a according to the first
embodiment. On the other hand, the sixth board 31b to be bonded to
the fifth board 31b is different from the second board 1b according
to the first embodiment, a notch 8 being formed thereto. Layering
the sixth board 31b to which the notch 8 has been formed in this
way on the plate-shaped fifth board 31a forms the fifth cover
member 31 including an inflow port at one end and a groove 15
extending from the inflow port.
[0103] A recess-forming through hole 4 is formed to, of the seventh
board 32a and eighth board 32b making up the cover member 32, the
seventh board 32a disposed below. Layering the eighth board 32b on
the upper face of the seventh board 32 to which the recess-forming
through hole 4 has been formed, forms the cover member 32 with the
element-accommodating recess 5 on the lower face. Note that the
eighth board 32b is basically the same as the fourth board 2b
according to the first embodiment.
[0104] Also, the biosensor 200 includes a hydrophilic film 34 on
the bottom face of the groove 5, as illustrated in FIG. 11. On the
other hand, the sixth board 31 is formed of a hydrophobic material.
Accordingly, the analyte solution basically flows into the channel
formed of the groove 5, and the analyte solution does not readily
enter into the gap between the first protective member 21 and the
upper face of the sixth board 31 and the gap between the second
protective member 22 and the upper face of the sixth board 31.
Accordingly, short-circuiting among ends 19e of the first
extracting electrodes 19 and so forth by the analyte solution is
suppressed.
Third Embodiment
[0105] Next, a biosensor 300 according to a third embodiment will
be described with reference to FIG. 12 through FIG. 15.
[0106] The biosensor 300 differs from the biosensor 100 according
to the above-described first embodiment with regard to the point of
including an assisting board 35 and to the structure of the portion
forming the first vibration space 23 and second vibration space 24
of the detecting element 3.
[0107] The assisting board 35 is a board introduced between the
first cover member 1 and second cover member 2 as illustrated in
FIG. 12, and the outer shape and size thereof is the same as that
of the second board 1b, for example. The thickness of the assisting
board 35 is, for example, 0.1 mm to 0.5 mm. The assisting board 35
is applied to the second board 1b below and the third board 2a
above, by way of adhesive agent or double-sided tape or the
like.
[0108] The element-accommodating recess 5 for accommodating a
detection element 40 is somewhat larger than the planar shape of
the detection element 40, as described in the first embodiment as
well. Accordingly, a gap is formed between the outer faces of the
detection element 40 and the inner walls of the
element-accommodating recess 5. The assisting board 35 serves to
block off this gap. At the same time, the assisting board 35 also
forms a part of the channel above the detection element 40.
[0109] The way in which the assisting board 35 blocks the gap
between the outer faces of the detection element 40 and the inner
walls of the element-accommodating recess 5 while also forming the
channel will be described with reference to FIG. 13 and FIG. 14.
FIG. 13(a) through FIG. 13(c) are perspective views illustrating a
state where certain members have been omitted from the biosensor
300. Specifically, FIG. 13(a) is a perspective view illustrating a
state with the second cover member 2 and assisting board 35
omitted, FIG. 13(b) is a perspective view illustrating a state with
the second cover member 2 omitted, and FIG. 13(c) is a perspective
view illustrating a state with the fourth board 2b omitted. FIG.
14(a) is a cross-sectional view corresponding to FIG. 4(a), and
FIG. 14(b) is a cross-sectional view corresponding to FIG.
4(b).
[0110] As illustrated in FIG. 13(a), a gap is formed in a state
where the detection element 40 is accommodated in the
element-accommodating recess 5, between the side faces of the
detection element 40 and the inner walls of the
element-accommodating recess 5. This gap is blocked off by the
assisting board 35 layered on the second board 2b, as illustrated
in FIG. 13(b).
[0111] Now, the structure of the detection element 40 used in the
biosensor 300 will be described. FIG. 15 is a perspective view of
the detection element 40 used in the biosensor 300. The detection
element 40 includes a frame member 37 disposed on the upper face of
the element substrate 10. The frame member 37 includes a through
hole at the middle portion to expose the two detection units 13, as
well as through holes to expose the IDT electrodes. That is to say,
the frame member 37 has a portion individually surrounding the
detection units 13 and the IDT electrodes.
[0112] The portions serving as the frame of the frame member 37 are
blocked by the assisting board 35, as illustrated in FIG. 14(a).
Thus, the assisting board 35 functions as a lid to block the frame
portions of the frame member 37, as well as serving to block the
gap between the side faces of the detection element 40 and the
inner walls of the element-accommodating recess 5. The first
vibration space 23 is formed by the portions surrounding the first
IDT electrodes 11 being blocked off, so the first IDT electrodes 11
are in a state of having been sealed within the first vibration
space 23. In the same way, the second vibration space 24 is formed
by the portions surrounding the second IDT electrodes 12 being
blocked off, so the second IDT electrode 12 are in a state of
having been sealed within the second vibration space 24. The
portions surrounding the detection units 13 are also blocked off,
with a space 38 formed at these portions.
[0113] The upper face of the frame member 37 is at the same
position as the upper face of the second board 1b. In other words,
the thickness of the frame member 37 is equal to the difference
between the thickness of the second board 1b and the thickness of
the element substrate 10. Forming the frame member 37 at this
thickness enables the portions which are the frame of the frame
member 37 to be blocked off, at the same time as blocking off the
gap between the side faces of the detection element 40 and the
inner walls of the element-accommodating recess 5. The thickness of
the frame member 37 is 50 .mu.m, for example.
[0114] Returning to FIG. 13(b), a first hole 41 and a second hole
42 are formed in the assisting board 35. These first hole 41 and
second hole 42 both communicate with portions within the frame
member 37 surrounding the detection units 13.
[0115] Thus, the third board 2a including the notch 8 is layered on
the upper face of the assisting board 35 including the first hole
41 and second hole 42. The first hole 41 and second hole 42 are
situated at positions over the notch 8 when the third board 2a is
layered on the assisting board 35. The notch 8 serves as the groove
15, meaning that the groove 15 and space 38 are connected by the
first hole 41 and second hole 42. The first hole 41 is formed
closer to the opening side end of the notch 8 which will become the
analyte solution inflow port, and the second hole 42 is formed
farther away from the opening side end of the notch 8 as compared
to the first hole 41. A partition 43 is formed at the portion
between the first hole 41 and second hole 42. The planar shapes of
the first hole 41 and second hole 42 may be optional shapes such as
circular, rectangular, or the like. The shapes and sizes of the
first hole 41 and second hole 42 may be the same or may be
different.
[0116] The analyte solution channel in the biosensor 300 structured
thus will be described with reference to the cross-sectional views
in FIG. 14. When the inflow port 14 is brought into contact with
the analyte solution, the analyte solution is suctioned by
capillary action into the channel formed by the groove 15, as
described in the first embodiment. Upon the analyte solution
flowing therein reaching the first hole 41, the analyte solution
enters the space 38 by the same capillary action via the first hole
41, so the space 38 is filled with the analyte solution. At this
time, the air in the space 38 is vented from the second hole 42.
Measurement regarding the analyte solution is performed in this
state. Thus, the space 38 is a part of the channel in the biosensor
300. At least the surface of the assisting board 35 is hydrophilic,
to facilitate capillary action. Formation of the partition 43
causes the analyte solution which has reached the partition 43 to
be held back and to enter the space 38 via the first hole 41.
[0117] The space 38, first vibration space 23, and second vibration
space 24, are spaces partitioned by the frame member 37 and
assisting board 35 as illustrated in FIG. 14(a), so analyte
solution which has flowed into the space 38 can be suppressed from
flowing into the first vibration space 23 and second vibration
space 24. Also, the gap between the side faces of the detection
element 3 and the inner walls of the element-accommodating recess 5
is blocked off by the assisting board 35, so the analyte solution
can be suppressed from flowing into that gap as well.
[0118] Thus, according to the biosensor 300, flow of analyte
solution to unnecessary portions can be suppressed, so
short-circuiting between the wiring 7 is suppressed. The amount of
analyte solution flowing through the channel can also be made
uniform.
[0119] Unlike the above-described embodiments, the wiring 7 of the
biosensor 300 is disposed on the bottommost layer, which is the
first board 1a. Accordingly, the fine metal wires 27 connecting the
wiring 7 to the ends 19e and 20e of the first and second first
extracting electrodes of the detection element 3 are inserted
downwards from the upper face of the of the detection element 3, so
the upward curving portion of the fine metal wires 27 is not very
high. This facilitates situating the peak of the fine metal wires
27 at a position lower than the height of the frame member 37.
Also, this does away with the need to perform separate work to
prevent the fine metal wires 27 from coming into contact with the
assisting board 35, so production efficiency improves. Note
however, the position of the fine metal wire 27 is not restricted
to this, and may be provided to the second board 1b in the same way
as with the first embodiment, for example. In cases where the fine
metal wires 27 will come into contact with the assisting board 35
if bonded in that state, the frame member 37 may be made thicker,
or a through hole may be provided to the assisting board 35 at the
region above the fine metal wires 27.
[0120] FIG. 16 is a cross-sectional view corresponding to FIG.
14(a), illustrating a modification 301 of the biosensor 300. While
the assisting board 35 in the biosensor 300 described above also
functions as a lid for the frame member 37, a second frame member
37b is provided separately from the assisting board 35 with this
modification.
[0121] FIG. 17 illustrates a perspective view of a detection
element 41 used in the modification 301. The detection element 41
differs from the detection element 40 illustrated in FIG. 15 with
regard to the structure of the frame member 37. The frame member 37
of the modification 301 includes a first frame member 37a and
second frame member 37b layered on the first frame member 37a. The
structure of the first frame member 37a is the same as that of the
frame member 37 of the biosensor 300, having portions surrounding
the two detection units 13 and IDT electrodes. The external shape
and size of the second frame member 37b is the same as that of the
first frame member 37a in plan view, but through holes are not
formed at portions corresponding to the first IDT electrodes 11 and
second IDT electrodes 12. Accordingly, the portion surrounding the
first IDT electrodes 11 is blocked off by the second frame member
37b so as to form the first vibration space 23, and the portion
surrounding the second IDT electrodes 12 is blocked off by the
second frame member 37b in the same way to form the second
vibration space 24. On the other hand, a through hole which is the
same shape and size of that in the first frame member 37a is formed
in the second frame member 37b at the region directly above the
detection units 13. This portion is blocked off by the assisting
board 35 so as to form the space 38 serving as part of the
channel.
[0122] Constructing the frame member 37 thus increases the area of
contact between the assisting board 35 and frame member 37, so the
assisting board 35 and a lid member 39 can be strongly bonded.
Fourth Embodiment
[0123] Next, a biosensor 400 according to a fourth embodiment will
be described with reference to FIG. 18 through FIG. 20.
[0124] The biosensor 400 differs from the biosensor 100 according
to the first embodiment described above, with regard to the point
of including an assisting board 44.
[0125] The assisting board 44 is a board introduced between the
first cover member 1 and second cover member 2 as illustrated in
FIG. 18, and the outer shape and size thereof is the same as that
of the third board 2a, for example. The thickness of the assisting
board 44 is, for example, 0.1 mm to 0.5 mm. The assisting board 44
is applied to the second board 1b below and the third board 2a
above, by way of adhesive agent or double-sided tape or the like. A
hole portion 45 is formed in the assisting board 44 so that the
detection units 13 of the detection element 3 are exposed when the
assisting board 44 is layered on the first cover member 1. Situated
on either side of the hole portion 45 are a third hole portion 45
and fourth through hole 46, having the same function as the first
through hole 16 and second through hole 17 in the third board 2a of
the biosensor 100 according to the first embodiment, as described
later.
[0126] The assisting board 44 serves to isolate the analyte
solution channel from the gap formed between the side faces of the
detection element 3 and the inner walls of the
element-accommodating recess 5. This will be described with
reference to FIG. 19 and FIG. 20. FIG. 19(a) through FIG. 19(c) are
perspective views illustrating a state where certain members have
been omitted from the biosensor 400. Specifically, FIG. 19(a) is a
perspective view illustrating a state with the second cover member
2 and assisting board 44 omitted, FIG. 19(b) is a perspective view
illustrating a state with the second cover member 2 omitted, and
FIG. 19(c) is a perspective view illustrating a state with the
fourth board 2b of the second cover member 2 omitted. FIG. 20(a) is
a cross-sectional view corresponding to FIG. 4(a), and FIG. 20(b)
is a cross-sectional view corresponding to FIG. 4(b).
[0127] As illustrated in FIG. 19(a), a gap is formed in a state
where the detection element 3 is accommodated in the
element-accommodating recess 5, between the side faces of the
detection element 3 and the inner walls of the
element-accommodating recess 5. Layering the assisting board 44
thereupon exposes a part of the detection element 3 from the hole
portion 45 in the assisting board 44, as illustrated in FIG. 19(b).
The hole portion 45 is formed to a size such that the perimeter
thereof is situated inwards from the perimeter of the detection
element 3. Thus, of the gap formed between the side faces of the
detection element 3 and the inner walls of the
element-accommodating recess 5 of the biosensor 400, the gap
portions situated at both ends in the x direction (gap portions
following the y direction) are situated beneath the assisting board
44. That is to say, of the gap formed between the side faces of the
detection element 3 and the inner walls of the
element-accommodating recess 5, the gap portions situated at both
ends in the x direction are blocked off. On the other hand, of the
gap formed between the side faces of the detection element 3 and
the inner walls of the element-accommodating recess 5 of the
biosensor 400, the gap portions situated at both ends in the y
direction (gap portions following the x direction) are exposed from
the third through hole 46 and fourth through hole 47.
[0128] The third board 2a in which is formed the notch 8 is layered
on the assisting board 44 layered on the first cover member 1. The
hole portion 45 to expose the detection element 3 is formed to the
assisting board 44, so the detection units 13 are exposed from the
notch 8 in plan view in the state illustrated in FIG. 19(c).
[0129] The analyte solution channel in the biosensor 400
constructed thus is basically the same as that of the biosensor 100
according to the first embodiment, as illustrated by the
cross-sectional views in FIG. 20. That is to say, when the inflow
port 14 is brought into contact with the analyte solution, the
analyte solution flows into the channel formed by the groove 15 by
capillary action. The analyte solution which has flowed in reaches
the detection units 13, and measurement is performed.
[0130] At this time, the portions of the gap formed between the
side faces of the detection element 3 and the inner walls of the
element-accommodating recess 5 that overlap the groove 15 are
blocked by the assisting board 44 as illustrated in FIG. 20(b), so
the analyte solution is kept from entering the gap. Also, the
portions of the gap formed between the side faces of the detection
element 3 and the inner walls of the element-accommodating recess 5
that are orthogonal to the groove 15 (gaps visible in FIG. 20(a))
are not blocked off by the assisting board 44, but the assisting
board 44 can keep the analyte solution from entering these gaps.
The reason is that the channel and gaps are partitioned by a third
partition 48 which is the portion between the hole portion 45 and
third through hole 46 of the assisting board 44, and a fourth
partition 49 which is the portion between the hole portion 45 and
fourth through hole 47 of the assisting board 44, as illustrated in
FIG. 20(a).
[0131] Thus, according to the biosensor 400, flow of analyte
solution to unnecessary portions can be suppressed, so
short-circuiting between the wiring 7 is suppressed. Also, there is
hardly any flow of analyte solution to unnecessary portions other
than the channel, so the amount of analyte solution regarding which
measurement is to be performed can be made uniform.
[0132] The present invention is not restricted to the above
embodiments, and may be carried out in various modes.
[0133] In the above embodiments, description has been made
regarding an arrangement where a detection unit 13 includes a metal
film and an aptamer fixed to the surface of the metal film.
However, in cases where the target matter in the analyte solution
reacts with the metal film, the detection unit 13 may be configured
including only the metal film, without using the aptamer. Further,
an arrangement may be made where the metal film is not used, and
the region between the first IDT electrodes 11 and second IDT
electrodes 12 on the surface of the element substrate 10 which is a
piezoelectric substrate is used as the detection unit 13. In this
case, physical properties of the analyte solution such as viscosity
is detected by directly applying the analyte solution to the
surface of the element substrate 10. More specifically, change in
the phase of SAWs due to the viscosity and so forth of the analyte
solution on the detection unit 13 changing can be read.
[0134] Also, while description has been made in the above
embodiments regarding an arrangement where the detection element 3
is a surface acoustic wave device, the detection element 3 is not
restricted to this, and a detection element 3 in which has been
formed an optical waveguide so that surface plasmon resonance
occurs, may be used. In this case, change in refractive index of
light or the like at the detection unit is read. Moreover, a
detection element 3 including an oscillator formed on a
piezoelectric substrate such as crystal, may be used. In this case,
change in oscillation frequency of the oscillator is read.
[0135] Also, multiple types of devices may coexist on the same
substrate for the detection element 3. For example, an enzyme
electrode for the enzyme electrode method may be situated next to a
SAW device. In this case, measurement according to the enzyme
method is enabled in addition to the immunization method using
antibodies or aptamers, increasing the number of items which can be
tested at one time.
[0136] Also, while an example has been illustrated in the above
embodiments where the first cover member 1 is formed of the first
board 1a and second board 1b, and the second cover member 2 is
formed of the third board 2a and fourth board 2b, the present
invention is not restricted to this, and one of the boards may be
integrated. For example, a first cover member 1 in which the first
board 1a and second board 1b are integrally formed may be used.
[0137] Also, while an example has been illustrated in the above
embodiments where one detection element 3 is provided, multiple
detection elements 3 may be provided. In this case, one
element-accommodating recess 5 may be formed for each detection
element 3, or an elongated element-accommodating recess 5 may be
formed to accommodate all of the detection elements 3.
[0138] Also, the modifications of biosensors and forms of the
components described in the embodiments may be applied to
biosensors according to other embodiments, such as applying a
modification of the biosensor 100 according to the first embodiment
to the biosensor 200 according to the second embodiment, without
departing from the technical idea of the present invention.
REFERENCE SIGNS LIST
[0139] 1 first cover member [0140] 2 second cover member [0141] 3
detection element [0142] 4 recess-forming through hole [0143] 5
element-accommodating recess [0144] 8 notch [0145] 10 element
substrate [0146] 11 first IDT electrode [0147] 12 second IDT
electrode [0148] 13 detection unit [0149] 14 inflow port [0150] 15
groove [0151] 16 first through hole [0152] 17 second through hole
[0153] 18 vent hole [0154] 19 first extracting electrode [0155] 20
second extracting electrode [0156] 21 first protective member
[0157] 22 second protective member [0158] 23 first vibration space
[0159] 24 second vibration space [0160] 31 mounting member [0161]
35 assisting board
* * * * *